Round axial fan with balancing structure

ABSTRACT

A round axial fan with balancing structure includes a hub; a ring-shaped band located around an outer side of the hub to thereby define an annular flow passage between the hub and the ring-shaped band; a plurality of blades located in the annular flow passage; and a plurality of recesses circumferentially spaced on and along the ring-shaped band, each of the recesses internally defining a receiving space for at least one balancing element to fit therein. With these arrangements, it is able to achieve weight balance of the round axial fan for the latter to rotate in a balanced state and to avoid any vibration due to unbalanced rotation of the round axial fan.

FIELD OF THE INVENTION

The present invention relates to a balancing structure, and more particularly to a round axial fan using such balancing structure to enable quick adjustment of the weight balance of the round axial fan, so that the round axial fan can rotate stably and material and labor costs therefor can be reduced.

BACKGROUND OF THE INVENTION

Electronic information products, including computers, have now become very popular among consumers and provide very wide applications. Consumers' wide demands also lead to rapid technical development in the electronic information industry. While the current electronic information products have increasingly upgraded computing speed and access capacity, the heat produced by the components in the electronic information products during high-speed operation thereof also increases. To remove the heat produced by the components from the electronic information products, heat sinks and cooling fans are usually provided in the electronic information products at positions of heat source.

A round axial fan is one of many different types of cooling fans. The round axial fan includes a hub, a plurality of blades radially outward extended from the hub, and a ring-shaped band integrally connected to the radially outer ends of the blades. The round axial fan is formed by injection molding. In the process of injection molding, there are times the injection-molding material is not uniformly injected to thereby result in uneven weight distribution of the hub, the blades or the ring-shaped band. The uneven weight distribution of the hub, the blades or the ring-shaped band has adverse influence on the balanced rotation of the round axial fan. That is, when the weight distribution of the hub, the blades or the ring-shaped band is uneven, the whole round axial fan would tilt during rotation to result in abrasion and vibration of the central shaft of the round axial fan relative to the bearing cup of the base supporting the round axial fan. The abrasion and vibration of the central shaft not only produces noise, but also accelerates the fatigue of the central shaft of the round axial fan to shorten the service life thereof. The fan device using the round axial fan would have reduced overall quality and provide poor heat dissipation effect.

To solve the problem of uneven weight distribution of the round axial fan, there are manufacturers who try to adjust the uneven weight distribution by locally providing weights on the hub of the round axial fan. FIG. 1 is a perspective view showing a conventional round axial fan with balancing structure. The conventional round axial fan 70 includes a hub 71 and a ring-shaped band 72. At least one blade 73 is provided between the hub 71 and the ring-shaped band 72. A plurality of recesses 711 is formed on the hub 71, and weights can be fitted in the recesses 711. The radius of the hub 71 relative to a center of the round axial fan 70 is smaller than the radius of the ring-shaped band 72 relative to the center of the round axial fan 70. In the case the round axial fan 70 tilts during rotation due to uneven weight distribution of the fan 70, weights are directly fitted in correct recesses 711 to balance the weight distribution of the fan 70. However, since there is a difference between the radii of the hub 71 and the ring-shaped band 72, the weights fitted in the recesses 711 on the hub 71 must be several times as heavy as the ring-shaped band 72 to reach the required balance. Therefore, the cost for providing the weights on the hub 71 is high. Further, with the weights fitted on the hub 71, the round axial fan 70 in rotating is still subject to tilting due to the uneven weight distribution of the ring-shaped band 72 and the large radius thereof. As a result, the abrasion and vibration of the central shaft of the round axial fan 70 relative to the bearing cup on the base of the fan is increased and requires more time and labor to adjust the overall weight distribution of the round axial fan 70.

In brief, the conventional round axial fan with balancing structure has the following disadvantages: (1) By fitting the weights on the hub, increased material for the weights is needed to achieve the purpose of balancing the fan; (2) the balance achieved by fitting the weights on the hub is easily adversely affected by the large radius and the uneven weight distribution of the ring-shaped band; and (3) additional material and labor costs are required to adjust the weight distribution of the round axial fan.

It is therefore tried by the inventor to develop an improved round axial fan with balancing structure in order to overcome the disadvantages in the prior art.

SUMMARY OF THE INVENTION

A primary object of the present invention is to provide a round axial fan with balancing structure, so that the round axial fan can be quickly adjusted to achieve balanced rotation and avoid damaged blades during rotation of the fan.

To achieve the above and other objects, the round axial fan with balancing structure according to the present invention includes a hub; a ring-shaped band located around an outer side of the hub to thereby define an annular flow passage between the hub and the ring-shaped band; a plurality of blades located in the annular flow passage, the blades respectively having a radially inner end connected to an outer circumferential surface of the hub and a radially outer end connected to an inner circumferential surface of the ring-shaped band; and a plurality of recesses circumferentially spaced on and along the ring-shaped band, each of the recesses internally defining a receiving space for at least one balancing element to fit therein. With these arrangements, it is able to adjust a weight distribution of the round axial fan for the latter to rotate in a balanced state.

BRIEF DESCRIPTION OF THE DRAWINGS

The structure and the technical means adopted by the present invention to achieve the above and other objects can be best understood by referring to the following detailed description of the preferred embodiments and the accompanying drawings, wherein

FIG. 1 is a perspective view showing a conventional round axial fan with balancing structure;

FIG. 2 is a perspective view showing a round axial fan with balancing structure according to a first preferred embodiment of the present invention;

FIG. 3 is a sectioned side view of FIG. 2;

FIG. 4 is an exploded sectional view showing the round axial fan of the present invention is assembled to a base to provide a fan device;

FIG. 5 is an assembled view of FIG. 4;

FIG. 6 is a top perspective view of the fan device of FIG. 5 with a balancing element to be tight-fitted in one of many recesses formed on the round axial fan;

FIG. 7 is a sectional view of FIG. 6;

FIG. 8 is a sectioned side view of a round axial fan with balancing structure according to a second preferred embodiment of the present invention;

FIG. 9 is a sectioned side view of a round axial fan with balancing structure according to a third preferred embodiment of the present invention;

FIG. 10 is a sectioned side view of a round axial fan with balancing structure according to a fourth preferred embodiment of the present invention; and

FIG. 11 is a sectioned side view of a round axial fan with balancing structure according to a fifth preferred embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention will now be described with some preferred embodiments thereof and with reference to the accompanying drawings. For the purpose of easy to understand, elements that are the same in the preferred embodiments are denoted by the same reference numerals.

Please refer to FIGS. 2 and 3 that are perspective and sectioned side views, respectively, of a round axial fan with balancing structure according to a first preferred embodiment of the present invention. As shown, the round axial fan 10 includes a hub 20 and a ring-shaped band 30 located around an outer side of the hub 20 to thereby define an annular flow passage 31 between the hub 20 and the ring-shaped band 30. The ring-shaped band 30 has a first end face 32 and a second end face 33 respectively located at an upper and a lower side of the ring-shaped band 30. A radius of the first end face 32 relative to a center of the hub 20 may be larger than, equal to, or smaller than a radius of the second end face 33 relative to the center of the hub 20. In the illustrated first preferred embodiment, the radius of the first end face 32 relative to the center of the hub 20 is equal to the radius of the second end face 33 relative to the center of the hub 20.

In the annular flow passage 31, there are provided a plurality of blades 40. The blades 40 are spaced along an outer circumferential surface of the hub 20, i.e. a surface of the hub 20 facing toward the ring-shaped band 30, to radially outward extend and connect to an inner circumferential surface of the ring-shaped band 30, i.e. a surface of the band 30 facing toward the hub 20. More specifically, the blades 40 each have a radially inner end 41 connected to the outer circumferential surface of the hub 20 and a radially outer end 42 connected to the inner circumferential surface of the ring-shaped band 30. A plurality of recesses 34 is formed on the first end face 32 of the ring-shaped band 30. The recesses 34 are circumferentially spaced along the first end face 32 and respectively define a receiving space 341 therein.

Please refer to FIGS. 4 and 5 at the same time. In the first preferred embodiment, the hub 20 internally defines a rearward opened hollow space for a magnetic ring 21 to fitly bear on an inner circumferential surface of the hub 20. A central shaft 22 is provided in the magnetic ring 21 to locate at a center thereof and is therefore also located at the center of the hub 20. The round axial fan 10 can be assembled to a base 50. The base 50 has a forward extended bearing cup 51 formed thereon for receiving the central shaft 22 therein, and a stator 52 fitted around an outer side of the bearing cup 51. The round axial fan 10 is concentrically assembled to the base 50 with the central shaft 22 serving as a center, so as to complete a fan device.

When the fan device is supplied with electric current and turned on, an electromagnetic induction effect between the magnetic ring 21 on the round axial fan 10 and the stator 52 on the base 50 is produced, bringing the hub 20 and the ring-shaped band 30 to rotate about the central shaft 22 on the base 50. When the round axial fan 10 rotates, it guides airflow to move and accordingly produces air convection to dissipate heat produced by a heat-producing object.

Please refer to FIGS. 6 and 7 at the same time. The recesses 34 are circumferentially spaced along the first end face 32 of the ring-shaped band 30. Each of the recesses 34 internally defines a receiving space 341 for at least one balancing element 60 to tightly fit therein. When the round axial fan 10 shows an unbalanced state and/or vibrates while rotating due to uneven weight distribution of the hub 20, the ring-shaped band 30 or the blades 40, at least one balancing element 60 can be tightly fitted in at least one of the recesses 34 to adjust the weight distribution of the hub 20, the ring-shaped band 30, or the blades 40, so that the round axial fan 10 can rotate in a balanced state. Compared to the weight distribution adjustment conducted on the hub 20 in the prior art, the weight distribution adjustment conducted on the ring-shaped band 30 in the present invention is more effective because a longer arm of force is available. Therefore, the purpose of adjusting the weight distribution of the hub 2, the ring-shaped band 30 or the blades 40 can be achieved with less number of balancing elements 60 to save the material thereof, and the condition of a tilted round axial fan 10 during rotation thereof caused by non-uniform radius and weight distribution of the hub 20 and the ring-shaped band 30 can be avoided to thereby save the time and labor for mounting the round axial fan 10.

By fitting the balancing element or elements 60 in suitable recess or recesses 34 to accurately adjust the weight distribution of the hub 20, the ring-shaped band 30 or the blades 40 when there is any weight difference existing in the hub 20, the ring-shaped band 30 or the blades 40, the round axial fan 10 can always rotate in a balanced and stable state to protect the blades 40 from damage during rotation thereof and to reduce undesired abrasion and vibration of the components of the round axial fan 10, so as to extend the usable life of the round axial fan 10.

FIGS. 8 and 9 are sectioned side views of second and third preferred embodiments, respectively, of the round axial fan according to the present invention. In the second preferred embodiment as shown in FIG. 8, the recesses 34 are provided on the second end face 33 of the ring-shaped band 30; and in the third preferred embodiment as shown in FIG. 9, the recesses 34 are provided on both the first and the second end face 32, 33 of the ring-shaped band 30. In both cases of the second and third embodiments, the balancing elements 60 are tight-fitted in the recesses 34. In the case non-uniform weight distribution is found in the hub 20, the ring-shaped band 30 or the blades 40, or between the first and the second end face 32, 33 of the band 30, such non-uniform weight distribution can be adjusted by fitting at least one balancing element 60 in at least one of the recesses 34, so that the round axial fan 10 can rotate in a balanced state.

The radius of the first end face 32 relative to the center of the hub 20 can be larger than the radius of the second end face 33 relative to the center of the hub 20 according to actual need, as a fourth preferred embodiment of the present invention shown in FIG. 10. In this case, the recesses 34 are formed on the first end face 32. Alternatively, the radius of the second end face 33 relative to the center of the hub 20 can be larger than the radius of the first end face 32 relative to the center of the hub 20 according to actual need, as a fifth preferred embodiment of the present invention shown in FIG. 11. In the latter case, the recesses 34 are formed on the second end face 33. By suitably fitting the balancing elements 60 in the right recesses 34, the weight distribution of the hub 20, the ring-shaped band 30 or the blades 40 can be adjusted for the whole round axial fan 10 to rotate in a balanced manner.

In conclusion, the round axial fan with balancing structure according to the present invention has the following advantages: (1) by fitting the balancing elements on the ring-shaped band to adjust the weight distribution of different components of the round axial fan, the number of the balancing elements to be used can be reduced; (2) by fitting the balancing elements on the ring-shaped band to adjust the weight distribution of different components of the round axial fan, it is able to avoid adverse influence on the balance of the round axial fan by the large radius and uneven weight of the ring-shaped band; (3) material for the balancing elements can be reduced; (4) cost for mounting the round axial fan can be reduced; and (5) the service life of the round axial fan can be prolonged.

The present invention has been described with some preferred embodiments thereof and it is understood that many changes and modifications in the described embodiments can be carried out without departing from the scope and the spirit of the invention that is intended to be limited only by the appended claims. 

1. A round axial fan with balancing structure, comprising: a hub; a ring-shaped band located around an outer side of the hub to thereby define an annular flow passage between the hub and the ring-shaped band; a plurality of blades located in the annular flow passage, the blades respectively having a radially inner end connected to an outer circumferential surface of the hub and a radially outer end connected to an inner circumferential surface of the ring-shaped band; and a plurality of recesses circumferentially spaced on and along the ring-shaped band, each of the recesses internally defining a receiving space for at least one balancing element to fit therein; whereby a weight distribution of the round axial fan can be adjusted by fitting the balancing elements in right ones of the recesses for the round axial fan to rotate in a balanced state.
 2. The round axial fan with balancing structure as claimed in claim 1, further comprising a magnetic ring fitted to an inner circumferential surface of the hub.
 3. The round axial fan with balancing structure as claimed in claim 1, further comprising a central shaft located at a center of the hub.
 4. The round axial fan with balancing structure as claimed in claim 1, wherein the recesses are circumferentially spaced on and along end faces of the ring-shaped band.
 5. The round axial fan with balancing structure as claimed in claim 1, wherein the ring-shaped band has a first end face and a second end face separately located at two opposite sides of the ring-shaped band.
 6. The round axial fan with balancing structure as claimed in claim 5, wherein the recesses are circumferentially spaced on and along at least one of the first or/and the second end face of the ring-shaped band.
 7. The round axial fan with balancing structure as claimed in claim 5, wherein a radius of the first end face relative to a center of the hub is equal to a radius of the second end face relative to the center of the hub.
 8. The round axial fan with balancing structure as claimed in claim 5, wherein a radius of the first end face relative to a center of the hub is larger than a radius of the second end face relative to the center of the hub.
 9. The round axial fan with balancing structure as claimed in claim 5, wherein a radius of the second end face relative to a center of the hub is larger than a radius of the first end face relative to the center of the hub. 